Bleaching straw.



STATES PATENT OFFICE.

PERCY EDGAR WIOKI-IAM, OF LONDON, ENGLAND, ASSIGNOR TO BADISCHE ANILIN &SODA FABRIK, OF LUDWIGSI-IAFEN-ON-TI-IE-RHINE, GERMANY, A CORPORATION.

BLEACI-IING STRAW.

No Drawing.

To all whom it may concern Be it known that I, PERCY EDGAR VVIOK- HAM,traveler, subject of the King of England, residing at London, England,have invented new and useful Improvements in Bleaching Straw, of whichthe following is a specification.

In bleaching straw by means of hydrosullites, as hitherto practised, thestraw is treated with a dilute solution of hydrosulfite at ordinarytemperature. Under these conditions the bleaching action is but slightand the effect obtained is not by itself sufiicient to satisfy practicalrequirements, so that the bleaching has been supplemented by the use ofother bleaching agents, besides the hydrosulfite, usually by hydrogenperoxid. I have found that the bleaching action of hydrosulfites can beconsiderably increased if the bleaching be efiected at a raisedtemperature, for instance at from aboutjfi? to {55 0., instead of atordinary temperature. I add to the bleaching solu tion an alkali, or asalt having an alkaline reaction; such, for example, as soda, sodium phgsphatg, or the like. After treatment in this manner, the straw can beworked up in the usual, or any suitable, way, being subjected to theusual, or any suitable, clearing and finishing treatments. It is, insome cases, advantageous, or necessary, to use two, or more,hydrosulfite baths in succession.

In carrying out my invention it is advisable that the hydrosulfite bathor, when two or more are used in succession, the first hydrosulfitebath, remains alkaline, and it is also preferred that, in the lattercase, the second and any succeeding bath or baths be maintainedalkaline, as, if the bath or baths, be allowed to become acid, the shadeof the straw sometimes appears to suffer and the hydrosulfite decomposesmore rapidly. Thgn sodium phosphate is employed in the bath,onba'ths,it"appears both to assist in maintaining the bath, or baths,alkaline and also to exercise a beneficial influence, as when sodiumphosphate is employed the straw is generally obtained of a lighter shadeafter being finished and dried than is the case when sodium phosphate isnot employed.

The following are examples of how this invention can be carried intopractical effect, but the invention is not confined to these examples.The parts are by weight.

Specification of Letters Patent.

Application filed. May 20, 1911.

Patented May 28,1912.

Serial No. 628,502.

Example 1: Dissolve one thousand parts of powdered sodium hydrosulfite,five hundred parts of crystallized sodium phosphate, and three hundredparts of calcined soda, in one hundred thousand parts of cold water.Introduce the straw into this solution and gradually raise thetemperature to about from fifty-five to sixty-five degrees centrigrade;maintain this temperature for a few hours longer and then coolgradually. Remove the straw and thoroughly rinse it, and finish it bytreatment for, say, two or three hours in a bath containing about twoparts of oxalic acid in one thousand parts of soft water and having atemperature of, say, from thirty to forty degrees centigrade. Remove thestraw and thoroughly rinse and dry it.

Example 2 Wash straw plaits in the usual way. Prepare a cold bleachingbat-h as follows :sodium phosphate ten parts per thousand and sodiumhydrosulfite (anhydrous) three and one-third parts per thousand of thebath, and add sufficient sodium "car bonate, or potassium carbonate,tothe bath so that it not only becomes distinctly alkaline, but remainsalkaline to the end of the treatment. Introduce the straw into the coldbath and after, say, about two or three hours raise the temperature,gradually, to about forty degrees centigrade and keep it at thistemperature for, say, from twelve to fifteen hours, and then raise thetemperature to sixty degrees centigrade. Allow the bath and its contentsto cool and then remove the straw and stove it for about half an hourbefore drying. a

For certain kinds of straw, for instance Chinese mottled plait, theprocedure hereinbefore described should preferably be repeated once ortwice. The straw is subsequently subjected to any usual, or suitable,clearing and finishing treatments with oxalic acid and potassiumcarbonate (separately or in combination), with excess of potassiumcarbonate, and dried with sulfur stoving.

Now what I claim is 1. The process of bleaching straw by treating itwith a hydrosulfite in an alkaline bleaching bath at a raisedtemperature substantially as hereinbefore described.

2. The process of bleaching straw by treating it with a hydrosulfite ata raised temperature in an alkaline bleaching bath containing sodiumphosphate, substantially In testimony whereof I have hereunto set ashereinbefore described. my hand in the presence of two subscribing 10 3.The process 01": bleaching straw by witnesses.

treating with a hydrosulfite at a tempera- PERCY EDGAR ,ICKHAM.

ture of iroln fifty-five to sixty-five degrees Centigrade in an alkalinebleaching bath \Vitnesses:

containing sodium phosphate substantially HUGH ROBERTSON STEWART,

as hereinbeiore described. PERCY ARTHUR MOORE.

Copies of tlus patent may be obtained for five cents each, by addressingthe Commissioner of Patents. Washington, D. G.

